代码改变世界

leetcode - N-Queens

2013-11-22 23:01  张汉生  阅读(202)  评论(0)    收藏  举报

 

 1 class Solution {
 2 public:
 3     void generateResults(vector<vector<string> > &rlts, int n, int index,  int * cur, bool * flag1, bool * flag2, bool* flag3){
 4     for (int i=0; i<n; i++){
 5         int j = index+i;
 6         int k = index-i+n-1;
 7         if (flag1[i] || flag2[j] || flag3[k]){
 8             continue;
 9         }
10         flag1[i]=true;
11         flag2[j]=true;
12         flag3[k]=true;
13         cur[index] = i;
14         if (index==n-1){
15         vector<string> rlt;
16         for (int p=0; p<n; p++){
17             string s="";
18             for (int q=0; q<n; q++){
19             if (cur[p]==q)
20                 s+='Q';
21             else s+='.';
22             }
23             rlt.push_back(s);
24         }
25         rlts.push_back(rlt);
26         }
27         else generateResults(rlts,n,index+1,cur,flag1,flag2,flag3);
28         flag1[i]=false;
29         flag2[j]=false;
30         flag3[k]=false;
31     }
32     }
33 
34     vector<vector<string> > solveNQueens(int n) {
35     // IMPORTANT: Please reset any member data you declared, as
36     // the same Solution instance will be reused for each test case.
37     vector<vector<string> > rlts;
38     if (n<=0)
39         return rlts;
40     int * cur = new int[n];
41     bool * flag1 = new bool[n];
42     bool * flag2 = new bool[2*n-1];
43     bool * flag3 = new bool[2*n-1];
44     for (int i=0; i<n; i++){
45         flag1[i]=false;
46         cur[i] = 0;
47     }
48     for (int i=0; i<2*n-1; i++){
49         flag2[i]=false;
50         flag3[i]=false;
51     }
52     generateResults(rlts,n,0,cur,flag1,flag2,flag3);
53     delete []cur;
54     delete []flag1;
55     delete []flag2;
56     delete []flag3;
57     return rlts;
58     }
59 };